Product composed of a mixture of expanded synthetic thermoplastic beads mixed with and molded with materials having a different density



B. OXEL July 22, 1969 3,457,217

PRODUCT COMPOSED OF A MIXTURE OF EXPANDED SYNTHETIC THERMOPLASTIC BEADSMIXED WITH AND MOLDED WITH MATERIALS HAVING A DIFFERENT DENSITY OriginalFiled Nov. 9, 1961 2 Sheets-Sheet 1 INVENTOR. asa'rou oxm.

ERIC Y. MUNSON July 22, 1969 a. OXEL PRODUCT COMPOSED OF A MIXTURE OFEXPANDED SYNTHETIC THERMOPLASTIC BEADS MIXED WITH AND MOLDED WITHMATERIALS HAVING A DIFFERENT DENSITY 2 Sheets-Sheet 2 Original FiledNov. 9, 1961 I I f l I I p I I INVENTOR. BERTON OXEL "n nun.--"

ERIC Y. MUNSON Hired tates atet PRODUCT tZGMPUSED OF A MKXTURE F EX-PANDED SYNTHETIC THERMGPLAETHC BEADS MIXED WlTH AND MQ'LDED WiTHMATERIALS HAVING A DIFFERENT DENSITY Berton Oxel, New (Iastle, Pa.,assignor to Dyfoarn orporation, New tlastle, Pa, a corporation ofPennsyivania Continuation of application Ser. No. 400,337, Sept. 30,1964, which is a division of application Ser. No. 151,368, Nov. 9. 1961,now Patent No. 3,164,860, dated Jan. 12, 1965. This application May 8,1967, Ser. No.

lat. Cl. (108i 47/08, 45/04 US. Cl. 260- 51 2 Ciaims ABSTRACT OF THEDESQLQSURE This provides a molded thermoplastic product composed of amixture of synthetic thermoplastic granules molded with vermiculite. Thegranules form a continuous matrix and the vermiculite is substantiallyuniformly dis tributed throughout the product.

This a continuation of application Ser. No. 400,337, filed Sept. 30,1964 and now abandoned which in turn is a divsion of application Ser.No. 151,368, filed Nov. 9, 1961, now Patent No. 3,164,860.

Expanded polystyrene and other similar thermoplastic materials areemployed for many useful purposes, but when used alone and without theaddition of some sort of binding or supporting material, its tendency tocrumblue or disintegrate often becomes evident, particularly at hightempertaures. It is therefore desirable, for some purposes andparticularly when the thermoplastic beads are used in the production ofa board or sheet, that some additional and possibly heavier material bemixed with it, which material will have such characteristics as toenable it to provide tenacity and body tending to hold the expandedthermoplastic beads together in a manner to retard crumbling and providea mixture of strength and durability.

It is therefore one of the objects of the present invention to provide aproduct composed of pre-expanded synthetic thermoplastic material suchas polystyrene beads, and materials of different densities and/ ordifferent particle size, such as vermiculite, perlite and other mineralas well as metal substances and plastic substances in liquid form willbe thoroughly mixed or blended together and can be conveyed directly bythe mixing or blending means into a molding section wherein the mixedmaterial will be subjected to heat and controlled and regulatedpressure, resulting in further expansion and in the consolidation of theingredients.

It is another object of the invention to provide a molded product from amethod of making a pie-expanded synthetic thermoplastic material in amixture with a heavier material in granular form, such as for example,vermiculite, with the granules of such heavier material thoroughly mixedwith thermoplastic and substantially uniformly distributed throughoutthe mixture, and in molding the mixture so produced with the assurancethat the molded product will contain the equal distribution of theparticles of thermoplastic and vermiculite as was attained by the mixingstep.

It is further an object of the invention to provide a molded productproduced in a mixing apparatus for the mixture of two materials ofdifferent densities and by which the normal tendency of the material ofgreater density to descend to the bottom of the mixing chamber will begreatly retarded, with the result that the mixture that is fed to themolding chamber or between molding belts, such as is suggested forexample in co-pending application Ser. No. 258,105, filed Feb. 4, 1963,will be one in which the heavier material will be equally distributedthroughout the molded product.

It is still a further object of the invention to provide a moldedproduct, composed of a mixture of synthetic thermoplastic, such asexpanded polystyrene, and other material such as vermiculite, or othermineral substances, metal particles, as well as other heavier plasticmaterials and the like in granular or liquid form, in which the beads orparticles of the thermoplastic will tend to be spaced or separated to amarked degree by the intervening other substances, thus being separatedthereby and resulting in a structure of improved heat-resistingcharacteristics.

More particularly, the invention includes the provision of a mixing andfeeding unit, including a multi-section hopper in which the differentmaterials are separately contained; in spiral conveying means locatedbelow the hopper at the outlets of the same; of means for regulating thefeeding of at least one of the materials to the conveying means; ofelements provided on the spiral conveyors for assuring a completemixture of the ingredients; of a heated mold chamber in which themixture is deposited by the conveying means, the mold chamber includinga movable mold wall that is operative to compress the material betweenit and a fixed mold wall, and in means for coupling the unit to themovable mold wall, and in means for moving the mixing and feeding unitin a manner to cause the regulatable compression of the material in themold chamber between the movable and fixed walls of the same. It should,of course, be understood that instead of moving the mixing and feedingunits, the latter may remain stationary and instead the mold chamber maybe moved relative to the mixing and feeding units.

With these and other objects to be hereinafter set forth in view, I havedevised the arrangement of parts to be described and more particularlypointed out in the claims appended hereto.

In the accompanying drawings, wherein an illustrative embodiment of theinvention is disclosed,

FIG. 1 is a vertical sectional View of an apparatus constructed inaccordance with the invention, and

FIG. 2 is a horizontal sectional view, taken substantially on the line2-2 of FIG. 1, looking in the direction of the arrows.

According to the present embodiment of the invention as disclosed in thedrawings, the improved apparatus contemplates the feeding of thedifferent materials from two separate hopper compartments into a gang ofspiral screw feeders or conveyors which not only tend to feed thesematerials to the molding means, but which because of mixing elementsprovided on the shafts of the screw conveyors, tend to secure completemixture of the materials and this despite the fact that one of thematerials is heavier than the other and hence exhibits a tendency todescend to the bottom of the mixing chamber.

The materials thus thoroughly mixed as above stated are conveyed by thespiral or screw conveyors to a molding section, an example of which isdisclosed at the left in both figures of the drawings, and in which theapplication of heat and pressure on the mixed material takes place.

The apparatus includes a hopper, generally indicated at 1, which isdivided by a vertical partition 2, into the two chambers generallyindicated respectively at 3 and 4. Chamber 3 contains the syntheticplastic material which may be pro-expanded polystyrene beads 15 orglobules of, for example, a density of one pound per cubic foot.

This chamber of the hopper is filled with the polystyrene through aninlet 5, through which the material can if desired, be airborne,permitting the material to drop down into the chamber 3, while the airescapes through the screen top 6 provided on the chamber 3.

The chamber 4 of the hopper receives the mineral or other particleshereinbefore mentioned, such as particles 16. These expanded granulesare loaded into the chamber 4 through the inlet 7, through which thismaterial can be airborne, the material falling down into the chamber 4,while the air escapes through the screen top 8.

Located at the lower end of the hopper 1 are four screw conveyors,indicated respectively at 9, 10, 11 and 12 in FIG. 2. It should beunderstood, however, that a lesser or greater number of screw conveyorsmay be used. Material received from the chambers 3 and 4 is received bythese convyors; is stirred or mixed by the mixing blades 14 provided onthe shafts of the screw conveyors and is moved by the conveyors into amolding chamber 17.

The four screw conveyors are rotated by means of a variable-speedelectric motor 18 mounted on a supporting bracket 19, said motor havingits shaft provided with a double sprocket 20, engaged by a chain 21extending to a sprocket 22 provided on a shaft of the screw conveyor 9.Screw conveyor shaft 30 carries a gear 29 which is in mesh with anddrives a gear 27 on the shaft 28 of the screw conveyor 10. Screwconveyors 11 and 12 are thus driven in opposite directions, but sincethese conveyors are of opposite thread, the feed of the material by bothof them will be in the same direction or toward and into the moldingchamber 17. Gear 24 is in mesh with and drives a gear 25 mounted on theshaft 2 6 of the screw conveyor 12 which is thus driven on the samedirection as the screw conveyor 10. Gear 29 is in mesh with and drives agear 27 on the shaft 28 of the screw conveyor 10 and thus rotativelydrives said conveyor in the same direction as conveyor 9. The bottomwall 31 of the chamber 3 of the hopper is apertured as shown at 32 sothat the polystyrene beads or globules will be received by the screwconveyors and moved thereby toward the left as viewed in FIG. 1.Rotatively mounted in the lower outlet end of the chamber 4 is apaddlewheel feeder 33, the same extending across the lower end of thechamber 4 and having its shaft 34 provided with a sprocket 35 engaged bya drive chain 36, extending from a sprocket 37 provided on the shaft ofa variable speed electric motor 38, mounted on a supporting bracket 39.This arrangement in such that by the speed of rotation of thepaddlewheel feeder and the capacity of the pockets in the feeder, theproportion of the vermiculite or other material particles 16 to thepolystyrene beads is regulatable. For example, 1 to 1 /2 per lb. percubic foot of the polystyrene to 6 lbs. per cubic foot of thevermiculite, might be used.

The four screw conveyors 9 to 12 inclusive extend beyond the hopper 1 intubes or sleeves 40 which enter into the interior of the mold chamber 17and connect to and pass through a movable mold wall 41 closely fittingwithin the molding chamber 17 and movable as a piston within the same.To eifect the axial movement of the mold wall 41 within the mold chamber17, the feeding apparatus is made movable as a unit. For this purpose,the hopper 1 and the parts associated'therewith are provided with legs42 and 43, the legs 42 having Wheels 44 supported on rails 45 mounted ona floor or other support 46. Wheels 47 are carried by axles in the legs43 which wheels also ride on the rails 45.

The axle 48 On which the wheels 44 are mounted, carries a sprocket 49engaged by a chain 50 extending over a sprocket 51 carried by the shaftof a variable speed motor 52 supported on the bracket 53. Thisarrangement is such that by the operation of the motor 52 the mold wall41 can be moved from the dotted line position shown in FIG. 1 to anydesired position with respect to the fixed end wall 54 provided on themold chamber 17.

The mold chamber is supported on the legs 65 and has an inner foraminouswall 55 jacketed by an outer wall 56, with a stem inlet 57 communicatingwith the space 53 located between the walls and causing the steam topass through the perforations in the inner wall 55 to reach and expandthe mixed materials 59 contained in the mold chamber and under pressureby the movable mold wall 41. A cover member 69 is hinged at 61 at thetop of the mold chamber, the cover having an inner foraminous wall 61and an outer jacketing wall 62, the steam enter ing into the spacebetween the walls 61 and 62 and reaching the mixed material 59 bypassage through the openings in the wall 61.

From the foregoing, the operation of the improved apparatus and methodwill be readily understood.

The heads of the thermoplastic material such as those of polystyrene,are rounded and are usually of a diameter of approximately .1 to 6 mm.As a result, they roll readily and operate with very little frictionagainst the blades of the screw conveyors. This friction is increasedsomewhat by the addition of the vermiculite. As the mixture is conveyedby the screws, the friction between the material and the screw bladesand the walls of the channels in which the blades operate is furtherincreased and compression is produced. The maximum compression imposedon the mixture is, of course, produced in the mold chamber 17.

The beads of the thermoplastic material, or polystyrene, descend in thechamber 3 to reach the screw conveyors, and they mix with the particlesof the other material, such as vermiculite that are fed to the screwconveyors in regulatable quantity by means of the paddle-wheel feeder33. The mixing blades 14 provided on the shafts of the several screwconveyors are effective to secure thorough mixing of the two differentmaterials, and this despite the greater weight of the one of them, assuch materials are being fed by the screw conveyors and into the moldchamber 17.

The mixed materials, thus moved and mixed by the screw conveyors, areforced thereby into the mold chamber and are compressed between themovable mold wall 41 and the fixed mold wall 54. The desired andregulatable compression is produced by movement of the mixing andconveying unit toward the left in FIG. 1 while the material is being fedinto the mold chamber until the required degree of pressure is reached,the steam injected into the mold provides for a baking and expansion ofthe mixture at a temperature of to degrees centigrade and results in animproved product.

Due to the fact that the conveyor screws tend to feed more of the mixedmaterial than there is space for in the molding chamber, a pressure isbuilt up therein which is applied to the conveyor screws. The pressuremay be built up as desired and to accord to the capacity possessed bythe conveyor screws. The pressure employed is that which is mostdesirable for the particular product to be produced. The compression orpressure imposed on the material must at least rise to a degree that itprevents the heavier ingriedients from settling and sinking to thebottom of the mixture. If that was to occur the obtaining of a uniformboard or sheet would not be had.

As previously mentioned, the compression is determined by the capacityof the conveyor screws as well as by the durability and strength of themolding chamber. By applying higher pressure, the volume per unit ofweight is increased due to the fact that a larger amount of the materialis fed into the molding chamber. This method results in the advantagethat the volume per unit of weight can be varied to the desired extent.

At the location where the different materials are mixed together namely,below the outlets of the two hopper sections, the pressure is no higherthan the weight of the materials themselves. Therefore, the mixing ofthe two materials must be thorough and that is attained by the describedstructure.

The degree of compression in the molding section can be observed througha manometer and when the compression reaches a point Where itsmaintenance is to be constant, it can be maintained by the displacementof the feeding apparatus. The motor 52 of low speed serves to propel theentire feeding apparatus at the desired speed so that the compressionrecorded on the monometer can be maintained.

At the conclusion of the molding operation as above described, thematerial is allowed to cool and it is then removed from the mold and thenext molding operation is carried out.

While it is herein suggested that the mixing and feeding apparatusherein described shall deliver its output of the mixed materials into amold of the construction illustrated, it will be apparent that it mightbe used for the production of material according to the co-pendingapplication Ser. No. 258,105 or in association with other structuresthat result in continuous production of the product.

With respect to the liquid thermoplastic this can be an adhesive whichwill set with or without heat after the particles have passed throughthe mixing screws. Rubber resin based adhesives could be used. Whenbeing heated in the mold, the solvent will disappear and thethermoplastic will adhere the mixed particles together. Such liquidcould also be a vinyl plastisol dissolved in alcohol. The liquid mayalso consist of thermo setting plastic such as a melamine or phenolcomposition.

The product produced by the apparatus and method herein described is onein which a uniform distribution of the vermiculite particles or otherparticles hereinbefore mentioned is had throughout the piece and inwhich such particles serve as spacing elements between the expandedthermoplastic beads, thus acting to separate and insulate them. Thethermal resistance of the vermiculite for example being rnore pronouncedthan that of the thermo-- plastic, a product more resistant to theeffect of heat than is the case when thermoplastic is solely used, isthe result.

I claim: 1. A molded thermoplastic product composed of: (a) a mixture ofexpanded synthetic thermoplastic granules and vermiculite, (b) saidgranules 'forming a continuous matrix, and (c) said vermiculite beingsubstantially uniformly distributed throughout the said product toseparate and support the granules. 2. A product as defined in claim 1wherein the said granules include pre-expanded polystyrene beads.

References Cited UNITED STATES PATENTS 2,744,291 5/ 1956 Stastny et al.

2,787,809 4/1957 Stastny.

2,958,905 11/1960 Newberg et al.

3,062,682 11/1962 Morgan et al.

3,345,442 10/1967 Oxel 264-51 3,086,247 4/1963 Rubens 26451 XR OTHERREFERENCES Hoppe, Peter: Lightweight Materials and Their Uses.[Translation of article (in German) in Kunststotfe, vol. 42, No. 12,December 1952, pp. 450-459], see pp. 6 and 15-16 of translation.

PHILIP E. ANDERSON, Primary Examiner US. Cl. X.R. 260-2.5; 264-

